melted. Wax solution, or stearine solution, rubbed up in a mortar, with steel filings, or cast-iron borings, also preserves them. The nitre of the gunpowder, however, attacks them, and ultimately rusts them; so that fireworks never so brilliant as when recently

are

charged.

SHELLS.

Shells are hollow paper globes, fired vertically, from mortars, or iron tubes. They are made of various sizes, from 3 inches in diameter to 16 inches. To make a 3-inch shell. Turn a wooden ball, 3 inches diameter; and, round the middle, that is, the equatorial circumference, cut a V groove, or triangular channel, deep enough to receive a piece of raw or naked match. Remove it from the lathe, and cut it into two halves at right angles to the groove, that is, round a meridional circumference. Construct a deal box, 4 inches square, 2 inches deep. Place one of the half globes, flat surface downwards, on the middle of the bottom of the box, and secure it with screws from underneath. Brush it, and the

inside of the box, all over, with sweet oil, with a camel's-hair pencil. Put some water into a basin; sprinkle into it as much plaster of paris as judged necessary; about 4 tablespoonfuls; pour off the water which floats above; stir up the plaster till homogeneous; pour it into the box; and, with a sash-tool held upright, beat the plaster in with the points of the bristles. Leave it to set.

Instead of having a wooden ball turned, a hemispherical concavity may be made by pressing, half way, into sand, one of the painted india-rubber balls sold at the toyshops; and pouring plaster over it. Or, a basin, an inch diameter larger than the intended shell, can have the plaster mixed up in it, till about threeparts full; and then the bottom of an oil flask can be pressed into it. A narrow strip of blue paper should be previously pasted round the oil flask, at the proper height, as a guide to know the proper depth to which it may be pressed. The plaster, when partly dry, must be neatly trimmed; and may be left, permanently, in the basin. Or, a stiff paper cylinder, or a tin cylinder, may be made, an inch larger in diameter than the diameter of the intended

shell put the oil flask into this, neck downwards, and pour in dry sand, till only the hemispherical bottom of the flask is left exposed; level the sand; oil the flask; and pour in plaster, as before. Be careful that the mould is not less than half-an-inch thick in any part. Or, one or two, or more halves of the zinc, or copper globes, used for ball-taps, may be obtained of the plumber, and used for moulds, without further preparation.

TO MAKE THE SHELLS.

Procure two kinds of paper; one imperial brown; the other sugar paper, printed paper, paper hangings, or any paper of a different colour from brown. The shell is supposed to be 3 inches; half as much again is 4; add to this for a flange, gives 6. Cut out a circular piece of the brown paper, 6 inches in diameter. Snip it all round with the scissors, in slits, reaching from the circumference, half way towards the centre; soak it in water, and lay it on a towel to drain. Have a piece of sponge, about the size of an orange; soak it also, and wring it. Place the piece of brown paper in the plaster concavity,

and press it in neatly with the sponge, in all directions; it will fill up the mould, and overhang all round; press the overhanging part flat, so that it forms a flange. Cut a piece of another coloured paper, into a strip, about 2 inches broad, and paste it well; then cut it across, backward and forward, like the letter W, which will reduce it to V-shaped triangles. Take these up, one by one; lay them in the brown paper, pasted side downwards, and press them neatly in with the sponge, making each slightly overlap the other. Let these also overhang to thicken the flange. This being done, proceed with a layer of brown; and so on, alternately, till it gauges about 2 inches across. The shell will, then, be about inch thick. Remove it, and proceed with others. The different-coloured papers enable the eye to detect, in a moment, whether any part is left uncovered. When dry, cut off the flange; make the edge straight: rub it on a sheet of glass paper, spread flat on a board. With a inch punch, cut a hole in the middle of one hemisphere; to it, glue another hemisphere and cover with two more layers of paper, or pieces of calico. The shell may, then,

of an

when dry, be filled with any kind of stars, or rains, that can be got through the hole. Along with the stars put of their weight of meal powder for a bursting charge: that is, if the stars weigh 4 ounces, as they probably will, put 4drams of mealpowder. Charge a roman candle case, inch internal, external diameter, with shell fuse (see fig. 59); saw it into inch lengths. Cut a piece of calico, 2 inches broad, and long enough to go twice round the fuse: paste the calico all over, and roll the fuse in it, so that the envelope is flush at one end, and overhangs one inch at the other. Glue this in the hole of the shell, the flush end, a, fig. 93, of course, inward the enveloped end, b, being to receive the match. of the fuse may be pushed in, of an inch left to project. With a printer's bodkin, or a stiletto, make a hole through both sides of the envelope, as at c and d; these holes are to be in a line with the groove; put through them a piece of raw match, in such a manner that it shall lie across the mouth of the fuse, and go, in the groove, round the shell underneath, and reach to e and f. Paste strips of paper over the